Hold Sway Puns

A young man sneaks into a rancher's pen late at night. The pen holds a large number of male cows, and the young man wants to try his hand at cow tipping...knocking the cow over while it's sleeping. The man tries tipping the 1st cow, but the cow simply sways a bit and wont fall over, no matter how hard he pushes.
Determined, the man moves to a smaller cow and pushes hard...again, the cow sways a bit but stays on its feet. Over and over, the young man keeps trying to knock a cow over...but ends up with the same results. After an hour of trying, the young man collapses to the ground...exhausted. In his frustration, he yells out "why cant I tip these darn cows over"?

The largest cow hears the young man, and slowly walks over to him. In a quiet voice, he says to the young man "We bulls wobble, but we don't fall down"